Traps are a relatively quick and easy method of defending a fortress. Unlike soldiers, they're always on duty, and, once set up, need less management. On the other hand, they are immobile and can only lie in wait for foes to walk over them. Traps can be built from the build->Traps/Levers menu. Most traps need one mechanism, a dwarf with the mechanic labor designated (more skilled mechanics take less time to build a trap), and at least one other component depending on the type of trap - a stone, a cage, or one or more weapons. They can be built indoors or outdoors on a vacant floor (natural or constructed). Traps will block the passage of caravan wagons.

Stone-fall, weapon and cage traps will be triggered by most hostile entities entering their tile, with the possible exception of thieves, flying creatures and other occasional nasty fun surprises. Any unconscious creature will trigger traps, including your own dwarves.

Note that only dwarves with the mechanic labor enabled will reload cage, stone, or weapon traps. In combat situations, mechanics have a nasty habit of wanting to reload (or clean) traps when they are triggered, regardless of who or what might be near them. Forbidding traps after they are built will keep Urist McSuicide from deciding to reload a trap in the middle of a siege. Just remember to unforbid them when things calm down, so the traps are all ready for next time. Note that forbidding a trap after it has been triggered doesn't help, as the job to refill the trap has already been issued in that case, so a mechanic will carry a stone out to the trap anyway. Alternatively, simply order your dwarves to stay within a safe burrow until any threats have been dealt with. If a cage trap has captured something while forbidden and been left alone for an extended period of time (nearly a year or longer) the caged individual escapes and you will get the announcement "Something has emptied a cage!". If put into a stockpile or claimed, captured individuals will be prevented from escaping.

It is possible to determine the state of a trap (loaded/unloaded) and the components it contains using the t query.

Traps can be deconstructed by pressing t to view the trap (or q, although the name of the trap will not be displayed until it is flagged for removal), followed by x to remove it. Deconstructing a trap leaves the components used in its creation on the ground around the tile. Traps destroyed by hostile action may return damaged objects.

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The simplest trap to construct, a stone-fall trap is essentially a stone suspended up in the air which is dropped on intruders when the trap is triggered. These are a popular defensive measure early on, as the components needed are readily available as soon as you start mining. A single stone trap will usually not severely wound or kill most animals and enemies, to the extent that this may be a bug. After being used they need to be reloaded with another stone by any dwarf with mechanicskill enabled, a task which your dwarves will see to automatically. The dwarf will generally not use the stone that just dropped, but a new one (would you want to put your hands on that gory mess?). Being that stonefall traps do not alert you of ambushes when triggered by hidden invaders, this can frequently lead your mechanics into peril. The weight of the stone used in the trap affects the amount of damage the trap does, but it's quite difficult to get your dwarves to use heavier stones, like galena, when loading the traps.

Weapon traps are similar in nature to stone-fall traps, and are triggered when any hostile creature stands on the trap. They contain between one and ten weapons, and tend to be much more reliable for outright killing or critically injuring invading creatures. Before you write off stone-fall traps as worse versions of weapon traps, note that weapon traps require you to have previously made weapons, making them more of an option somewhat later in the game. Any weapon can be used, including human weapons, training weapons, bows, traded weapons and weapons recovered from dead goblins. Think of it as fair retribution when goblins are sliced to pieces by their own axes!

You can also use the corkscrews that are normally used in screw pumps, or menacing spikes that are normally used in spike traps, or any of three specialist trap only weapons:

These weapons have all the material property advantages and disadvantages that normal weapons have. It should be noted that the trap weapons are larger than normal dwarf weapons, meaning they should be more effective than normal weapons made of equivalent materials. When triggered, this trap will "attack" the creature with all the weapons available to it, normally doing massive damage. This can also be very messy if the trap is loaded with cutting weapons, often creating an explosion of blood and dismembered body parts. Using blunt weapons reduces the mess somewhat, and you may wish to strategically place a Dwarven Bathtub nearby.

Weapon traps do not cause slightly suicidal mechanics to reset them after each triggering but instead reset automatically after an unknown period of time. However, there is a 50% chance that the victim will get stuck in the mechanism and cause the trap to jam (use t to check the trap), requiring a dwarf to remove the body. When the trap jams, the mechanic will automatically attempt to clean it, so forbidding the body (or forbidding the trap's mechanism in advance) may be necessary to save him from the victim's friends. Note that weapon traps will only jam if they directly kill the creature - if they instead inflict a mortal wound and cause the creature to bleed out, they will not jam.

When placing the trap you will be asked for a type of mechanism as normal, then asked to select weapons to use. The quality of your chosen mechanism matters[1]. At this point you will get a list of all stockpiled weapons in your fortress. +- will select different weapons and pressing "Enter/Return" adds 1 of the selected weapon to the trap; you can expand the selection to choose more carefully. Up to 10 weapons can be put in each trap and all weapons in the trap will attack at once when it is triggered (10 large serrated disks normally results in the unfortunate triggering creature leaving with fewer limbs than none of the limbs and several more torn apart organs than it came in with). When happy with your weapon selection press d to set the trap.

The triggering creature will defend from the trap's attacks just like from a dwarf's, by jumping away, dodging and blocking. This can be used in your favour if the trapped tile happens to be surrounded by pits.

Cage traps are different from the other trap types in that they do not directly kill or injure invaders. Instead, they capture the creature that triggers them in a cage. Despite the unfortunate lack of violence, this is still very effective as it completely neutralizes the target so that it can be dealt with later. After a creature is captured, it's stored in an animal stockpile if the current standing order is set (o-a). The trap will then be reset by hauling an empty cage to the trap's location. This is done automatically, as in, during a siege, by any dwarf with the Mechanics labor enabled. Cage traps will also alert you to ambushes when triggered by hidden invaders, making them a useful forward defense mechanism.

Most captured creatures do not require any nourishment and will survive being in a cage indefinitely; in fact, even submersion in water or magma appears to have no effect on caged creatures. It is possible for dwarves to bring water to cages, but this will only occur if you have someone friendly also locked in the cage - like a dwarf child snatched by a goblin. See below for how to remove things from a cage.

Cage traps will not capture every creature in the game, so you will need alternative defenses - titans and forgotten beasts (as well as certain other types of creatures) are immune to traps entirely and will waltz right past all of your carefully placed cages unless the cage has a giant cave spider web on it. A webbed cage trap will capture nearly anything; the only creatures it cannot capture are those immune to both cage traps and webbing, such as a web-spinning forgotten beast or a dwarf from your fortress on a Collect Webs job.

Cage traps are also useful for catching wild animals. This can be done by simply placing traps in areas where wild animals roam (this does not require a dwarf with the trapping labor enabled). The captured animals can be tamed (and sometimes trained into war animals!) at the kennels. See Animal trainer for more on training animals.

In the process of taming a wild animal, there is a chance that seeds will be left in the cage. Dwarves only load empty cages into traps. One way to remove the seeds and make the cage usable again is to dump them. First look at the cage in your Animal stockpile, then highlight the seed and press Enter to look at the seed, then press d to dump the seed.

The material a cage is made affects indirectly the speed at which it is assembled into the trap. Heavier cages take longer to assemble. The more skilled a dwarf is in the Mechanics skill, the less time he takes to assemble the cage.

With exception to the latter, cage material has no effect (beyond weight for hauling, value of finished trap, and the fact that elf merchants will get angry if the cage is wooden). A glass terrarium is just as strong as a steel cage.

To release a creature from a cage, build the cage (bj) and use q to unassign it. You can also simply assign the creature to a pasture or pit. To release a hostile creature (or wild animal) safely from a cage, build the cage and link the cage to a lever that can be remotely triggered. If you have many cages you need to empty out quickly see Mass pitting. Cages have no current limit to the amount of beasts you can put in them, so you can build one cage and assign all the beasts to that cage. Typical caveats of dealing with wild/hostile animals apply.

As with most traps, if a dwarf goes to sleep or is knocked unconscious over a cage trap, it will be triggered and the dwarf will be trapped. Unlike usual creatures, a caged dwarf can starve or die from dehydration.

Weapon traps trigger when a hostile creature steps on them. An upright spear/spike trap is different -- it must be triggered externally to cause the spears or spikes to spring up or to recede back down. When the spears/spikes spring up, any creature on the tile will be subject to possible impalement.

Placing the upright spear/spike trap does not require a mechanism, and it does not require the Mechanic labor. It only requires 1 to 10 spears or spikes. Linking it to a lever or a pressure plate will require a mechanism and must be performed by a Mechanic. Without such a link, the trap will not operate.

An often overlooked ability of an upright spike trap is that it also inflicts damage on a creature that falls onto it while it is deployed. And since they are built in the deployed state they can be quickly built to make a pit trap more lethal, without the need for extra mechanisms. However, you will still need some way to cause your victims to fall onto the spike from above in the first place, and the pit must be more than 1 z level deep for the spikes to cause damage. Note, however, that if any enemies survive the fall they may gain ridiculous weapon skills.Bug:6397

Shortcut: bTS

Components used: 1-10 spears or spikes, plus further mechanisms for linking to triggers.

All of the above traps other than Upright Spear use mechanisms in their construction. The quality of the mechanism used impacts weapon traps beyond their value however, in weapon traps the mechanism quality seems to act similarly to weapon skill in an entity and will play a part in determining whether a strike lands. Code analysis suggests that mechanism quality also impacts the effectiveness of stone fall traps, though it has no effect on cage traps.

You can create even more elaborate traps with imaginative use of pits, pressure plates, levers, grates, supports, water, and/or magma, creating sacrificial altars (blood for the Blood God!) and whatever else you can think of. Watching those goblins try to find a way out of your drowning chamber as it begins to fill is really quite satisfying. These are best made in a large, repeatable mass killing way. If you make a trap that kills 10 or so goblins that only works once and you have to rebuild it, wasting time you don't have during a siege, then you're not trying hard enough having too much fun.